A torando travels across the horizon on May 23, 2008, near Quinter, Kan. / AP/Steven Hausler, The Hays Daily News

by Rick Jervis, Doyle Rice and John Bacon, USA TODAY

by Rick Jervis, Doyle Rice and John Bacon, USA TODAY

GRANBURY, Texas - Authorities in north Texas sifted through the rubble Thursday left by the nation's most violent and deadly outburst of tornadoes in more than a year.

The storms left at least six people dead, dozens injured and scores of homes flattened.

Richland Hills Police Detective Tye Bell, an incident spokesman, said nearly 100 homes were destroyed and 250 people displaced by one twister that struck the subdivision of Rancho Brazos near Granbury, about 40 miles southwest of Fort Worth.

Damage to the subdivision reminded Bell of the destruction caused by the deadly tornadoes that struck Joplin, Mo., two years ago, though on a smaller scale. The Joplin tornado killed more than 150 people.

The National Weather Service in Fort Worth, citing preliminary reports, said as many as 12 tornadoes touched down Wednesday night in north Texas.

The weather service damage survey team in Granbury found EF-4 damage on the Fujita Scale of Tornado Intensity - wind speeds of 166-200 mph. EF-4 is the second-highest level on the scale.

The weather service conducted damage surveys to determine the exact strength of the tornadoes.

Deeds said 37 people were treated at hospitals. The injuries ranged from lost limbs to minor bumps and bruises, he said.

"We have never seen a community catastrophe with as many injuries as we did through last night," said Kyle McCombs, chief of staff at Lake Granbury Medical Center, where he has worked for more than 12 years.

Emergency teams rushed 18 bulldozers into the subdivision to clear the way for rescue teams and to look for people trapped in the debris. The city said 19 buildings and 17 mobile homes were destroyed. An additional 59 buildings and two mobile homes were damaged.

Much of the construction in Rancho Brazos in the past five years was done by Habitat for Humanity, the Fort Worth Star-Telegram reported.

The sheriff said more than 250 people were evacuated, many by bus.

"The house across from mine looked like it was destroyed," said Rancho Brazos resident Allacia Jenny, 22. "I saw power lines all over the place."

Officers "are going house to house" looking for residents trapped, injured or dead in the rubble of demolished homes near Lake Granbury, said Hood County Sheriff's Lt. Kathy Jiveden.

The Red Cross set up shelters for tornado victims at two churches.

In Cleburne, a town of 30,000 people 25 miles southeast of Granbury, Mayor Scott Cain declared a disaster, citing "wide damage, some injuries and loss of property." No fatalities or serious injuries were reported, he said.

The Cleburne tornado, reported to be a mile wide at one point, was given a preliminary rating of EF-3, the weather service said. That translates to wind speeds of 136-165 mph. The tornado left an 8-mile path of damage.

This was the nation's deadliest tornado outbreak since six people were killed in Woodward, Okla., on April 14, 2012.

Wednesday's storms that tore through the region were the result of a strong disturbance diving into northern Texas, AccuWeather meteorologist Anthony Sagliani reported. Warm and humid winds blowing from the Gulf of Mexico collided with hot and dry winds from West Texas, resulting in a twisting motion in the lower atmosphere.

A tornado also hit the small town of Millsap west of Fort Worth. Parker County Judge Mark Kelley said roof damage was reported on several houses and a barn was destroyed, but no injuries were reported. Another tornado was spotted at around 8 p.m. near Decatur in Wise County. Another was spotted 10 miles west of Weatherford.